NAIROBI (Reuters) - With its economies recovering, Africa needs to start rebuilding reserves and thinking about tightening spending to build defences against future crises, the head of the International Monetary Fund (IMF) said on Monday.

In Kenya as part of a three-country tour of Africa to examine its recovery from the crisis, Fund Managing Director Dominique Strauss-Kahn said it was still too early for many governments to withdraw emergency fiscal measures.

However, Africa's leaders must keep an eye on future disaster mitigation by ensuring they have sufficient reserves and the ability to boost short-term spending -- factors that allowed the poorest continent to weather the worst of last year's global economic storm.

"Africa is back, although a lot depends on a global recovery that is still in its early stages," Strauss-Kahn said in a speech at the University of Nairobi. "For many countries, it is still too early to remove the crutch."

"A major lesson from the crisis is that countries that sowed in times of plenty were able to reap in times of loss. Policy buffers must therefore be rebuilt to allow for future countercyclical responses, with fiscal policy and reserves. This is the first line of defence against adverse shocks."

He also urged African leaders to plan for unexpected problems by negotiating debt with flexible repayment terms, or taking out insurance against natural disasters.

The IMF is now projecting economic growth in the sub-Saharan region at 4.5 percent, below the 6-7 percent it enjoyed in years leading up to the global slowdown, but well above last year's estimates of expansion below 2 percent.

The Washington-based institution lent Africa a record $5 billion last year as global recession hit demand for its commodities and other exports, causing a sharp decline in government revenues.

Remittances from Africans living overseas -- an important source of income for many -- also declined.
However, more than 30 countries were able to maintain social spending at pre-crisis levels or above due to the prudence of economic policies in the boom years, Strauss Kahn said.

Despite the relatively positive outlook, he said Africa remained at risk from factors ranging from natural disasters to political upheaval and an over-reliance on single streams of revenue, such as mining exports.

"This is not the time to rest on our laurels. African remains highly vulnerable to economic dislocation from many different sources," he said. "Think about swings in commodity prices, natural disasters or instability in neighbouring countries."